While bond funds have some of the same positive characteristics of other mutual funds: spreading risk through diversification, professional management, etc., bond funds generally do not offer the key benefits that are characteristic of individual bonds.
Most investors are attracted to bonds for two reasons: Preservation of capital if held to redemption, and to lock in a known, steady stream of income. Bond funds do neither! Bond funds are shares of an entity that go on into perpetuity trading, leveraging, etc. a bunch of securities, many of which are bonds, but, there is no end date when you get back your principal, nor is there a guaranteed stream of income. Keep in mind that any guarantees are subject to the paying ability of the issuer. As a bond fund owner, you are simply a shareholder of this entity, and its dividends may be changed at any time in response to market conditions.